<template>
    <div>
        <div class="goods">
            <div class="menu-wrapper">
                <ul>
                    <!-- current -->
                    <li class="menu-item" v-for="(good,index) in goods" :key="index"
                      :class="{current: index === currentIndex}" @click="clickMenuItem(index)">
                        <span class="text bottom-border-1px">
                            <img class="icon" :src="good.icon" v-if="good.icon">
                            {{good.name}}
                        </span>
                    </li>
                </ul>
            </div>

            <div class="foods-wrapper">
                <ul ref="foodsUl">
                    <li class="food-list-hook" v-for="(good,index) in goods" :key="index">
                        <h1 class="title">{{good.name}}</h1>
                        <ul>
                            <li class="food-item bottom-border-1px" v-for="(food,index) in good.foods"
                             :key="index" @click="showFood(food)">
                                <div class="icon">
                                    <img width="57" height="57" :src="food.icon">
                                </div>
                                <div class="content">
                                    <h2 class="name">{{food.name}}</h2>
                                    <p class="desc">{{food.description}}</p>
                                    <div class="extra">
                                        <span class="count">月售 {{food.sellCount}} 份</span>
                                        <span>好评率 {{food.rating}}</span></div>
                                    <div class="price">
                                        <span class="now">￥{{food.price}}</span>
                                        <span class="old" v-if="food.oldPrice">￥{{food.oldPrice}}</span>
                                    </div>
                                    <div class="cartcontrol-wrapper">
                                        <CartControl :food="food"/>
                                    </div>
                                </div>
                            </li>
                        </ul>
                    </li>
                </ul>
            </div>
            <ShopCart/>
        </div>
        <Food :food="food" ref="food"/>
    </div>    
</template>

<script>
    import BScroll from 'better-scroll'
    import {mapState} from 'vuex'
    import CartControl from '../../../components/CartControl/CartControl.vue'
    import Food from '../../../components/Food/Food.vue'
    import ShopCart from '../../../components/ShopCart/ShopCart.vue'
    export default {
      data(){
        return {
          scrollY:0,  // 右侧滑动的Y轴坐标 (滑动过程时实时变化)
          tops:[],  // 所有右侧分类li的top组成的数组  (列表第一次显示后就不再变化)
          food:{}  // 需要显示的food
        }
      },
      mounted() {
          this.$store.dispatch('getShopGoods',() => { // 数据更新后执行
            this.$nextTick(()=>{ // 列表数据更新显示后执行

              this._initScroll()
              this._initTops()

            })
          })
      },
      computed:{
          ...mapState(['goods']),

          // 计算得到当前分类的下标
          currentIndex(){
            // 得到条件数据
            const {scrollY, tops} = this
            // 根据条件计算产生一个结果
            const index = tops.findIndex((top,index) => {
              // scrollY>=当前top && scrollY<下一个top
              return scrollY >= top && scrollY < tops[index + 1]
            })
            // 返回结果
            return index
          }
      },

      methods: {
        // 初始化滚动
        _initScroll(){
          new BScroll('.menu-wrapper',{
            click:true
          })
          this.foodsScroll = new BScroll('.foods-wrapper',{
            probeType: 2,  // 因为惯性滑动不会触发
            click:true
          })

          // 给右侧列表绑定scroll监听
          this.foodsScroll.on('scroll',({x,y})=>{
            console.log(x, y)
            this.scrollY = Math.abs(y)  //Math.abs：获取绝对值
          })
          // 给右侧列表绑定scrollEnd结束监听
          this.foodsScroll.on('scrollEnd',({x,y})=>{
            console.log('scrollEnd',x, y)
            this.scrollY = Math.abs(y)  //Math.abs：获取绝对值
          })
        },
        // 初始化tops
        _initTops(){
          // 1. 初始化tops
          const tops = []
          let top = 0
          tops.push(top)
          // 2. 收集
          // 找到所有分类的li
          const lis = this.$refs.foodsUl.getElementsByClassName('food-list-hook') //lis是伪数组
          Array.prototype.slice.call(lis).forEach(li => {
            top += li.clientHeight
            tops.push(top)
          })
          //3.更新数据
          this.tops = tops
        },

        clickMenuItem(index){
          // console.log(index)
          // 使用右侧列表滑动到对应的位置

          // 得到目标位置的scrollY
          const scrollY = this.tops[index]
          // 立即更新scrollY(让点击的分类项成为当前分类)
          this.scrollY = scrollY
          // 平滑滑动右侧列表
          this.foodsScroll.scrollTo(0, -scrollY, 300)
        },

        // 显示点击的food
        showFood(food){
          // 设置food
          this.food = food
          // 显示food组件 (在父组件中调用子组件对象的方法)
          this.$refs.food.toggleShow()
        }
      },

      components:{
        CartControl,
        Food,
        ShopCart
      }
    }
</script>

<style lang="stylus" rel="stylesheet/stylus">
  @import "../../../common/stylus/mixins.styl"
  .goods
    display: flex
    position: absolute
    top: 195px
    bottom: 46px
    width: 100%
    background: #fff;
    overflow: hidden
    .menu-wrapper
      flex: 0 0 80px
      width: 80px
      background: #f3f5f7
      .menu-item
        display: table
        height: 54px
        width: 56px
        padding: 0 12px
        line-height: 14px
        &.current
          position: relative
          z-index: 10
          margin-top: -1px
          background: #fff
          color: $green
          font-weight: 700
          .text
            border-none()
        .icon
          display: inline-block
          vertical-align: top
          width: 12px
          height: 12px
          margin-right: 2px
          background-size: 12px 12px
          background-repeat: no-repeat
        .text
          display: table-cell
          width: 56px
          vertical-align: middle
          bottom-border-1px(rgba(7, 17, 27, 0.1))
          font-size: 12px
    .foods-wrapper
      flex: 1
      .title
        padding-left: 14px
        height: 26px
        line-height: 26px
        border-left: 2px solid #d9dde1
        font-size: 12px
        color: rgb(147, 153, 159)
        background: #f3f5f7
      .food-item
        display: flex
        margin: 18px
        padding-bottom: 18px
        bottom-border-1px(rgba(7, 17, 27, 0.1))
        &:last-child
          border-none()
          margin-bottom: 0
        .icon
          flex: 0 0 57px
          margin-right: 10px
        .content
          flex: 1
          .name
            margin: 2px 0 8px 0
            height: 14px
            line-height: 14px
            font-size: 14px
            color: rgb(7, 17, 27)
          .desc, .extra
            line-height: 10px
            font-size: 10px
            color: rgb(147, 153, 159)
          .desc
            line-height: 12px
            margin-bottom: 8px
          .extra
            .count
              margin-right: 12px
          .price
            font-weight: 700
            line-height: 24px
            .now
              margin-right: 8px
              font-size: 14px
              color: rgb(240, 20, 20)
            .old
              text-decoration: line-through
              font-size: 10px
              color: rgb(147, 153, 159)
          .cartcontrol-wrapper
            position: absolute
            right: 0
            bottom: 12px
</style>
